docs: def action_aggregate(reader, *args):
      """Aggregate flow records by 5-tuple and print a tab-separated stream"""
      all_aggregated = aggregated_records(reader)
      first_row = next(all_aggregated)
      keys = sorted(first_row.keys())
      print(*keys, sep='\t')
  
      # Join the first row with the rest of the rows and print them
      iterable = chain([first_row], all_aggregated)
      for item in iterable:
          print(*[item[k] for k in keys], sep='\t')